Court insiders say Derek Chauvin’s attorney believes a prosecution witness may be helpful to Chauvin’s murder case. One officer can be heard on tape telling George Floyd it takes “a lot of oxygen” to talk as Floyd said he can’t breathe while Chauvin had his knee on his neck. Officer Nicole Mackenzie, the Minneapolis Police Department’s medical trainer, said “Just because they’re speaking doesn’t mean they’re breathing adequately.” During cross-examination, Mackenzie acknowledged officers may miss signs of problems with a patient if loud things are happening around them. Chauvin’s attorney said he will recall Mackenzie during Chauvin’s portion of the trial, and it’s expected he will focus on what he has called a “growing mob” during Floyd’s arrest. Former Minneapolis cop Chauvin is accused of killing Floyd last year by kneeling on his neck until he stopped breathing.